<!doctype html>
<html>
<meta charset="utf-8">
<style>
:first-child {
  display: table-header-group;
  margin-right: 10px;
}
</style>
<script>
"use strict";

addEventListener("DOMContentLoaded", () => {
  const editingHost = document.querySelector("span[contenteditable]");
  getSelection().collapse(editingHost, 0);
  editingHost.blur();
});

function onfocusout() {
  const selection = getSelection();
  const range = selection.getRangeAt(0);
  selection.modify("move", "left", "line");
  selection.addRange(range);
  document.execCommand("hiliteColor", false, "#5343B4");
}
</script>
<body>
<canvas> width="7"></canvas>
<textarea>AAA</textarea>
<fieldset onfocusout="onfocusout()">
<span contenteditable>
</span>
</fieldset>
</body>
</html>
